Sidebar icon change changes icon of pointed item

I'm still getting the same problem even though the following has been tried:

Step 1: Put the actual Dropbox.app in sidebar (so that we can get it's icon saved into the sidebar so we can copy the data later)

Step 2: in Terminal, execute killAll Finder (to make sure that the sidebar change gets written out to the file).

Step 2.5: Backup the file ~/Library/Preferences/com.apple.sidebarlists.plist

Step 3: This requires some program that can edit binary .plist files (xcode or Property List editor from the apple Developer Downloads work, at the very least). Open the file ~/Library/Preferences/com.apple.sidebarlists.plist in this program.

Step 4: Search for "Dropbox.app". Copy this entire string Icon.

Step 5: In the same file, find Dropbox folder's listing. Delete the text in its Icon field and paste in the value we just copied. Save the file.

Step 6: killAll Finder again to pick up changes. You should now be able to remove the Dropbox.app from your sidebar since it is fairly useless there.

I tried the above procedure but Finder seems not to accept the update of the file. Once I save the file and invoke killall again, nothing happens, even though the file retains the modifications just made. Only after reboot the file is restored back to the original version.

I then thought it could have been a matter of permissions, so created a copy of the orignal file, modified and saved. Then, I did a sudo rm com.apple.sidebarlists.plist && sudo cp <modified> com.apple.sidebarlists.plist && sudo chown com.apple.sidebarlists.plist root && sudo cmod u=+r com.apple.sidebarlists.plist
This way, I thought, Finder won't be able to update or do whatever to this file, being owned by root and being read only! Then I rebooted and voila! It seemed to work, the icon was there.....just for a few seconds!!!!! Then it switched back to the old one! I then looked in the terminal and saw that not only the contents of com.apple.sidebarlists.plist were changed back to the original values, but they were changed both the owner (me) and the permissions (-rw-r--r--@ instead of -r--r--r--@) !!!

After that I decided that I would have tried some kind of overkill: do the switch job using Ubuntu XD
disabled journaling of OSX disk, download Ubuntu 10.10, burn to disc, reboot into Ubuntu, mount with write permission enabled (thanks to journaling disabled) and switch files like before (rm com.apple.sidebarlists.plist && cp <modified> com.apple.sidebarlists.plist). I though that now it had to work, no matter what! so: umount, sudo reboot and boot OSX... which decides that somehow something was wrong and finds that that file was changed and had to be taken back to the original one (boot took two minutes, and a white bar told me that something was in progress)


I'm not doing any progress and even though this is a very little thing it is really ******* me off 😟


Anyway, it should be much more simpler than this to accomplish what I',m trying to do